A theoretical study of the local electronic structures of SiC polytypes

The electronic structure of four SiC polytypes has been computed by means of the LMTO (ASA+CC) method. It is shown that the results of the calculations are very sensitive to the choice of the atomic sphere radii, if the combined corrections are not taken into account in the ASA. The local electronic structure shows a different behaviour between the states in the cubic bilayers and those in the hexagonal ones. It is found that the interaction of c and h bilayers plays a major role, giving rise to changes in the polarity of the Si - C bonds and to charging of bilayers. The effect of the lattice distorsion on the local valence electron charge has been investigated and discussed.